<!doctype html>

<title>05 Properties - React From Zero</title>

<script src="https://unpkg.com/react@16.4.0/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16.4.0/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>

<div id="app"></div>

<script type="text/babel">
// Components, like elements, can use properties, too
function MyComponent(props) {
  return (
    <div className={props.className}>
      <h1>Hello</h1>
      <h2>{props.customData}</h2>
    </div>
  );
}

// Add the defaultProps (function-)property to set the defaults
// if nothing was provided by the user
MyComponent.defaultProps = {
  customData: "default-data",
  className: "default-class"
};

var reactElement = <MyComponent className="abc" customData="world" />;

// Which also works with an object and the spread (...) operator
var props = {
  className: "abc",
  customData: "world"
};

reactElement = <MyComponent {...props} />;

// This allows components with dynamic content
var planets = ["earth", "mars", "venus"];

// If an array is used as a "child node" each child needs a unique 
// key-property. This map call will return an array of components,
// like this example:
// [
//  <MyComponent className="myClass" customData={"earth"} key={0}/>,
//  <MyComponent className="myClass" customData={"mars"} key={1}/>,
//  <MyComponent className="myClass" customData={"venus"} key={2}/>
// ]
var elements = planets.map(function(planet, index) {
  return (
    <MyComponent
      className="myClass"
      customData={planet}
      key={index}
    />
  );
});

reactElement = <div>{elements}</div>;

var renderTarget = document.getElementById("app");

ReactDOM.render(reactElement, renderTarget);
</script>